Swarm testnet bootnodes

[mfw78]

Problem When looking at the packaging yaml, it's indicated that the default bootnodes are set for [/dnsaddr/testnet.ethswarm.org], despite the documentation at https://docs.ethswarm.org/docs/working-with-bee/configuration#--bootnode indicating that bootnodes for staging and testnets must be set explicitly.

Confusion from this ensues.

Solution To formalize the use of /dnsaddr/testnet.ethswarm.org for the public testnet. As such, the chain config should be set for goerli and the bootnodes (refer: https://github.com/ethersphere/bee/blob/49008fb6c7fa780b4a01c0c7559d539656ca1524/cmd/bee/cmd/start.go#L475).

If it is chosen not to do this, the documentation should be updated with a warning or caution to highlight that bootnodes must be specified for the public testnet.